Mike,
The imager was based on the guts of an inkjet printer. The head replaced by the 100mw UV laser. I think he was running the head motor open loop and using the plastic strip scale to time the pixels (laser pulses). So it scanned across a line quite fast but you have a lot of lines to write. The Y direction was by a stepper controled moving table under the head. For technical reasons he was only writing in one direction for each head pass and the head went full width even for small boards. IIRC the spot size was 2 -3 thousands. I think a 4" x 5" board would take on the order of 20 minutes to write.
This is a very old thread and for some reason I had trouble finding it agian.
Craig
--- In Homebrew_PCBs@yahoogroups.com, MIKE DURKIN <Patriot121@...> wrote:
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> How was the exposures times .. I see one 100mW and lots of 5mW,1mW pens ....
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> My wife owns a Silhouette SD crafting thingy .... wonder if the cutting head could be fitted with a pen ....
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> Mike KC7NOA
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> To: Homebrew_PCBs@yahoogroups.com
> From: cs6061@...
> Date: Sun, 1 Jan 2012 17:06:05 +0000
> Subject: [Homebrew_PCBs] Re: Photoresist
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> Jeff,
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> If you are interested in direct imaging a photo sensitized board search back through the posts around Nov of 09 for Volkan. He built a UV laser diode direct writer that did spectacular images. The 400 nm blue-ray lasers are available on ebay. He has some images posted under the Files secton of the forum. These UV lasers are very strong >> 100mW.
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> I took him a board I had coated in AQ3000 (water based photo resist) to try an image. Once we got the exposure set the image was amazing crisp.
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> Volkan alos built a drum photo plotter.
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> Both these project on my list of cool things to build.
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> Craig
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> --- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@> wrote:
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> > Hi Baxter,
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> > I read a message from a few months ago on the UV Pen discussion that you
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> > were experimenting with a UV LED and a microscope objective to focus the LED
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> > down for resist developing. How are your experiments going? Any findings
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> > yet?
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> > Jeff
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> > _____
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> > From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
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> > On Behalf Of bebx2000
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> > Sent: Tuesday, December 27, 2011 4:24 PM
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> > To: Homebrew_PCBs@yahoogroups.com
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> > Subject: [Homebrew_PCBs] Re: Photoresist
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> > Hi Jeff,
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> > I got your email. I have pretty much put my experiments with DIY
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> > photoresists on the backburner. The patent that I originally cited has very
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> > precise instructions for making your own. The application was for solder
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> > mask. I assembled all of the ingredients, but discovered that that I need a
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> > mixing mill to make a decent emulsion. Elmer's School Glue is basically the
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> > same formula, PVA and PVac plus surfactants and flow aids. I made up a batch
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> > using diazo as a sensitizer in the same proportion as the patent, coated a
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> > blank PCB with a soft hair brush (it levels very nicely because of the
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> > surfactants) and pre-baked it. I then took a transparency with some pads and
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> > traces and exposed it with a 150 watt metal halide UV source. The time was
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> > calculated from the mJ of the patent based upon the UV intensity as measured
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> > at the surface of the PCB with a UV radiometer.
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> > After exposure, I washed the board in water with a little gentle rubbing and
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> > the areas under the black part of the transparency washed away, but not
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> > perfectly. I didn't bother with the post-bake so perhaps this was part of
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> > the problem. I also tried just dipping a pre-baked board in a 1% solution of
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> > ammonium dichromate (as in the second patent), but the exposure time seemed
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> > to be off. All-in-all I think this is a viable concept, but one needs to
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> > have patience and setup a systematic sequence of experiments to establish
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> > the exposure time relative to the amount of sensitizer.
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> > Baxter
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> > N.B. I caution you in the use of ammonium dichromate. It really likes to
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> > cross-link collagen.
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> > --- In Homebrew_PCBs@yahoogroups.com
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> > <mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff Heiss" <jeff.heiss@>
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> > wrote:
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> > > I have been researching and have found that making your own resist looks
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> > > possible. The ingredients are polyvinyl alcohol (PVA) and ammonium
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> > > dichromate. An alternative is Elmers glue and ammonium dichromate. Baxter,
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> > > a member on here was performing experiments in this area. Maybe he can
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> > > chime in if he is reading?
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